Cellular Membrane Essay

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Cellular membranes are complex, two-dimensional fluids composed mainly of lipids and proteins, which are constantly in motion. Membrane lipids are organized in a bilayer (two monolayers of lipids forming a single membrane) whereas proteins are scattered throughout the bilayer. The most significant feature of all natural membranes is their flexibility or their ability to change shape without losing their integrity and becoming leaky. Since the forces holding the bilayer are weak non-covalent interactions, the lipids and many associated proteins in the bilayer are not rigidly held in place and the movement to individual lipids were allowed because they are not covalently anchored to one another. There are no barriers against rotation and lateral…show more content…
carbon chain length 16 and 18) pack well into a liquid-ordered state, but the kinks in unsaturated fatty acids interfere with this packing and prefers the liquid-disordered state. Shorter-chain lengths of fatty acyl groups were also favoring the liquid-disordered state.
 The sterol content of a membrane, which differs greatly with change in the organism, is another important element of lipid state. For the Sterol lipids, the rigid planar structure of the steroid nucleus positioned between fatty acyl side chains decreases the freedom of neighboring fatty acyl chains to move by rotation about their carbon–carbon bonds and forces acyl chains to their fully extended conformation. The presence of sterols thus condenses the fluidity in the core of the bilayer, and hence favors liquid-ordered phase and increases the thickness of the lipid leaflet.
 Cells regulate their lipid composition to achieve constant membrane fluidity and impermeability under various pH and physiologic conditions. For example, bacteria produce more unsaturated fatty acids and less saturated fatty acid when cultured at low temperatures than when cultured at higher temperatures. Due to this adjustment in lipid composition, membranes of bacteria cultured at high or low temperatures have about the same degree of

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